Thickness of Retro- and Sub-Orbicularis Oculi Fat in Thyroid Eye Disease: Comparison With Controls and Its Influential Factors.

[PURPOSE] To compare the thickness of the retro- and sub-orbicularis oculi fat (ROOF and SOOF) between patients with thyroid eye disease (TED) and controls via MRI and to determine factors influencing fat thickness.

[METHODS] This retrospective, comparative, case-control study included 136 patients (272 sides) with TED and 50 control patients (50 sides). The thickness of the ROOF and SOOF was measured on the quasi-sagittal plane through the optic nerve (the central plane) and 6 mm lateral and medial to the central plane at the level through the superior orbital rim and at the level just below the orbital septum in the lower eyelid, respectively.

[RESULTS] The ROOF and SOOF were thickest on the lateral plane (p < 0.050; Tukey Kramer post hoc test) and were significantly thicker in patients with TED than controls on all planes (p < 0.050; Student t test). Multivariate stepwise analysis showed that age, sex, clinical activity score, Hertel exophthalmometric values, and number of enlarged extraocular muscles are significant predictors of the ROOF and SOOF thickness in patients with TED (p < 0.050).

[CONCLUSIONS] Patients with TED had thicker ROOF and SOOF on all planes than controls with various factors influencing the thickness. These results may be helpful in planning rehabilitative blepharoplasty with removal of the ROOF and SOOF for correction of eyelid fullness in TED.